Help required - Spray painting my tinnie!

[sporty1]

Hi guys
I am looking a respraying the hull of my plate tinny, due to some self inflicted scratches and general misuse. The majority of the paintwork is in excellent condition so I have rubbed back the affected areas and today I tried etch priming them in preparation for the spraying to be done on Thursday. However as you can see from the attached photo all did not go entirely to plan. The majority of areas sprayed are fine but as with Murphys Law the two largest sections turned out as shown. It caused the paint to blister and peel off. (was there a contaminant in these areas? ) Should I was the areas down with a degreaser? Any suggestions appreciated.


90665

[Darren Mc]

Hi sporty1,
You'll need to sand the area right back again and next time try spraying the etch on very lightly as you don't need a thick coat and only over the bare ally spots as well. A little bit on the paint won't hurt.

What's happened is the solvent in the etch has reacted strongly with the thin edge of paint and fry'd it up. One light coat over the bare ally should be ok. By light I mean just heavy enough that you can just see a little gloss on the etch from an angle. Than you'll need to primed out past the whole patch to seal it all up and hopefully hold down that edge. Don't put to much thinners in the primer and again do light coats allowing plenty of flash off between coats.
Hope that helps mate.

[sporty1]

Thanks Darren, when you say prime out past the whole patch is this still with the same primer? And then do I continue to build up these thin coats? When have I done enough coats?

[Swanie1975]

dust a very light coat of etch on and wait until it goes completely dull, this means the solvents have flashed off (evaporated) and you can put another light coat on until coverage has occured. then do the same with the primer until it covers and you build up a fairly thick coat of primer to allow for sanding back but if you cut thru back to the etch you will need to re-prime. im assuming you are using two pack and all safety gear.

again the same process for the top coat of colour but for the last coat try to spray it with a nice wet-look finish without getting it so thick it runs or sags, thats the tricky part.

cheers ryan

[Darren Mc]

Het sporty1
Swanie1975 is spot on with his advice, and no the primer is a different product to the etch.
Generally with 2 PAC primer, the amount of thinners you put in determines how much build you will get. Less thinners means more build and vice versa. With your situation because of the sensitive paint edge underneath, less thinners in the primer will mean less solvent to potentially bite into that paint edge. If the sanded area feels nice and straight you won't need heaps of build(coats). If the patch feels a bit wobbly you'll need to block it with a block and sand paper.
A few questions,
Are you using 2pac or acrylic ?(probably should have asked this at the start)
Are you wet rubbing by hand or are you dry rubbing with a sander?
What colour are you painting it? Is it a solid colour or a metallic base coat?

[sporty1]

Hi Darren spraying 2 PAC did dry rubbing with a sander and if feels really smooth. painting a basic black as was the original coat.

[Darren Mc]

Ok that's all good, make your final rub minimum p500 grit dry sand paper, but no higher than p800.
If it's base coat black you'll need to put a couple of coats of clear over it.
If is a direct off the gun gloss black, it will only be the hardener mixed black that you'll paint.
The second option is the easiest and the cheapest of the two but the first one will be the most durable.
Also do make sure you use the correct safety gear ie mask and protective suit and eye protection and gloves. 2 PAC is pretty poisonous stuff hey.
You should really use a breathable air fed full face mask but for a one off a charcoal canister mask might do. Don't use one of those dust masks that wont do anything to protect you.

If you've got anymore questions I'll be glad to answer them.